package com.ff.javamonkey.xmodem;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.PrintWriter;

public class XModem1k {
	// Debugging
	private static final String TAG = "BluetoothTestActivity";
	
	private final int SECSIZE = 1024;
	private final int MAXERRORS = 10; // retry for 10 times
	
	// Protocol bytes
	private final char SOH = 0x01;
	private final char STX = 0x02;
	private final char EOT = 0x04;
	private final char ACK = 0x06; 
	private final char NAK = 0x15; // Base-10 value: 21
	private final char CAN = 0x18; // Base-10 value: 24
	private final char CRC = 0x43; // Base-10 value: 67
	
	// crctab calculated by Mark G. Mendel, Network Systems Corporation
	private final char crctable[] =
		{	0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5,
			0x60c6, 0x70e7, 0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad,
			0xe1ce, 0xf1ef, 0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294,
			0x72f7, 0x62d6, 0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c,
			0xf3ff, 0xe3de, 0x2462, 0x3443, 0x0420, 0x1401, 0x64e6, 0x74c7,
			0x44a4, 0x5485, 0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee, 0xf5cf,
			0xc5ac, 0xd58d, 0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6,
			0x5695, 0x46b4, 0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe,
			0xd79d, 0xc7bc, 0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861,
			0x2802, 0x3823, 0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969,
			0xa90a, 0xb92b, 0x5af5, 0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50,
			0x3a33, 0x2a12, 0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e, 0x9b79, 0x8b58,
			0xbb3b, 0xab1a, 0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03,
			0x0c60, 0x1c41, 0xedae, 0xfd8f, 0xcdec, 0xddcd, 0xad2a, 0xbd0b,
			0x8d68, 0x9d49, 0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32,
			0x1e51, 0x0e70, 0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a,
			0x9f59, 0x8f78, 0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d,
			0xf14e, 0xe16f, 0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025,
			0x7046, 0x6067, 0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c,
			0xe37f, 0xf35e, 0x02b1, 0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214,
			0x6277, 0x7256, 0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f,
			0xd52c, 0xc50d, 0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447,
			0x5424, 0x4405, 0xa7db, 0xb7fa, 0x8799, 0x97b8, 0xe75f, 0xf77e,
			0xc71d, 0xd73c, 0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657, 0x7676,
			0x4615, 0x5634, 0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9,
			0xb98a, 0xa9ab, 0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x08e1,
			0x3882, 0x28a3, 0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8,
			0xabbb, 0xbb9a, 0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0,
			0x2ab3, 0x3a92, 0xfd2e, 0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b,
			0x9de8, 0x8dc9, 0x7c26, 0x6c07, 0x5c64, 0x4c45, 0x3ca2, 0x2c83,
			0x1ce0, 0x0cc1, 0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba,
			0x8fd9, 0x9ff8, 0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2,
			0x0ed1, 0x1ef0	};
	
	protected DataInputStream inStream;
	protected DataOutputStream outStream;
	protected PrintWriter errStream;
	
	// file
	private String fileName;
	
	public XModem1k(DataInputStream dis, DataOutputStream dos, PrintWriter errs) {
		inStream = dis;
		outStream = dos;
		errStream = errs;
	}
	
	public XModem1k() {
		inStream = (DataInputStream)System.in;
		outStream = new DataOutputStream(System.out);
		errStream = new PrintWriter(System.err);
	}
	
	protected boolean gotChar;
	
	/**
	 * Send a file to the remote
	 */
	public boolean send(String tfile) throws IOException {
		fileName = tfile;
		char errorcount;
		byte blocknumber, character;
		byte[] sector = new byte[SECSIZE];
		int nbytes;
		
		DataInputStream dis;
		dis = new DataInputStream(new FileInputStream(tfile));
		errStream.println("file open, ready to send");
		System.out.println("file open, ready to send");
//		Log.i(TAG, "file open, ready to send");
		errorcount = 0;
		blocknumber = 0x01;
		
		gotChar = false;
		
		do {
			character = getChar();
//			Log.i(TAG, character == NAK ? "NAK" : "Not NAK");
			System.out.println("Initial character, obtained: " + (int)character);
			if (character == NAK || character == CRC) break;
//			Log.i(TAG, "Initial character, obtained: " + (int)character);
			gotChar = true;
			if (character != NAK || character != 'C') {
				++errorcount;
			}
		} while (character != NAK || character != 'C');
		
		System.out.println("Start Transmitting");
//		Log.i(TAG, "Start Transmitting");
		
		while ((nbytes = dis.read(sector))!=0) {
			if (nbytes <= -1) {
				break;
			}
			if (nbytes < SECSIZE)
				for (int i = nbytes; i < SECSIZE; i++)
					sector[i] = (byte)0xff;
			errorcount = 0;
			while (errorcount < MAXERRORS) {
				errStream.println("{" + blocknumber + "}");
				System.out.println("{" + (int)blocknumber + "}");
//				Log.i(TAG, "{" + (int)blocknumber + "}");
				char crc16 = crc16(sector);
				putChar(STX, "STX"); // header
				putChar(blocknumber, "BlockNumber");
				putChar(~blocknumber, "Inverse BlockNumber");
				putChar(sector, "Sector");
				putChar(crc16 >> 8, "Crc 16 high bit");
				putChar(crc16 & 0xff, "Crc 16 low bit");
				putChar(0x00, "null");
//				ByteArrayOutputStream tmpb = new ByteArrayOutputStream();
//				tmpb.write(STX);
//				tmpb.write(blocknumber);
//				tmpb.write(~blocknumber);
//				tmpb.write(sector);
//				tmpb.write(crc16 >> 8);
//				tmpb.write(crc16 & 0xff);
//				tmpb.write(0x00);
//				outStream.write(tmpb.toByteArray(),0,tmpb.size());
//				outStream.flush();
				if (getChar() != ACK) {
					++errorcount;
				}
				else
					break;
			}
			blocknumber = (byte)((++blocknumber) % 256);
		}
		boolean isAck = false;
		while (!isAck) {
			putChar(EOT, "EOT");
			isAck = getChar() == ACK;
		}
		errStream.println("Transmission complete.");
//		Log.i(TAG, "Transmission complete");
		return true;
	}
	
	protected byte getChar() throws IOException {
		byte something = (byte)inStream.read();
//		Log.i(TAG, "getChar from inStream " + (int)something);
		return something;
	}
	
	protected void putChar(int c, String debug) throws IOException {
//		Log.i(TAG, debug);
		System.out.println(debug);
    	outStream.writeByte(c);
    }
    
    protected void putChar(byte[] b, String debug) throws IOException {
//    	Log.i(TAG, debug + ", " + b.length);
    	System.out.println(debug + ", " + b.length);
    	outStream.write(b); 
    }
    
    protected void putChar(byte[] b, int c, String debug) throws IOException {
    	byte[] b2 = new byte[b.length+1];
    	int i = 0;
    	for (byte b1 : b) {
    		b2[i++] = b1;
    	}
    	b2[b2.length-1] = (byte)c;
    	outStream.write(b2);
    }
	
	/**
	 * unsigned short crc16_ccitt(const void *buf, int len) {
	register int counter;
	register unsigned short crc = 0;
	for (counter = 0; counter < len; counter++)
		crc = (crc << 8) ^ crc16tab[((crc >> 8) ^ *(char *) buf++) & 0x00FF];
	return crc;
}
	 */
	
	protected char crc16(byte[] bytes) {
		char crc = 0x0000;
		for (byte b: bytes) {
			crc = (char) ((crc << 8) ^ crctable[((crc >> 8) ^ b) & 0x00ff]);
		}
		return (char) (crc);
	}
}
